Foot operating control unit and system for air driven dental handpieces



March 29, 1966 M STAUNT FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES Original Filed April 1l, 1960 6 Sheets-Sheet l atm.

M. STAUNT March 29, 1966 FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES Original Filed April ll, 1960 6 Sheets-Sheet 2 t @Mwwsmw Xa /m INVENTOR.

March 29, 1966 M STAUNT 3,242,572

FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES Original Filed April ll, 1960 6 Sheets-Sheet 5 @363 DRIVE- wATEQ BLK.

I I IN VEN TOR.

29, 1966 M. sTAUNT FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES original Filed April 11, 195o 6 Sheets-Sheet arch 29, 1966 M. STAUNT FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES 6 Sheets-Sheet 5 Original Filed April ll. 1960 gwww Wl? ////.../I

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March 29, 1966 M, STAUNT 3,242,572

FOOT OPERATING CONTROL UNIT AND SYSTEM FOR AIR DRIVEN DENTAL HANDPIECES Original Filed April ll. 1960 6 Sheets-Sheet 6 INVENToR.

United States Patent O 3,242,572 FOOT PERATING CONTROL UNIT AND SYSTEM FR AIR DRIVEN DENTAL HANDPIECES Martin Staunt, Des Plaines, lil., assignor to American Hospital Supply Corporation, Evanston, Ill., a corporation of Illinois Continuation of application Ser. No. 197,036, May 23, 1962, which is a division of application Ser. No. 21,293, Apr. 11, 1960, now Patent No. 3,054,187. This application Mar. 18, 1965, Ser. N 444,909 3 Claims. (Cl. 32-27) The present invention relates to a foot operated control unit and system for air driven dental handpieces, and is particularly concerned with the provision of a system including a foot-operated unit for controlling the ow of drive air and chip-clearing air to a dental handpiece.

This application is a continuation of my copending application Serial No. 197,036, tiled May 23, 1962, now abandoned which is in turn a division of my prior application Serial No. 21,293, filed April ll, 1960, now Patent 3,054,187.

One of the objects of the present invention is the provision of an improved foot controller for air driven dental handpieces which is so constructed that a dentist is not required to shift his Weight, but only to rotate his foot upward or downward on the heel, causing his toe to operate upon the camming surface of the foot controller pedal to control the speed of operation of the handpiece.

Another object of the invention is the promotion of safety for the patient and the dentist and a reduction of fatigue on the part of both the patient and the dentist, and the reduction of time required for the preparation of cavities, and the promotion of steadiness on the part of the dentist in manipulating the cutting instrument when operating at high speeds or when removal of cuttings is desired.

A further object of the invention is to permit the dentist to change quickly from drilling to chip blast and back to drilling and to promote maximum visibility and higher accuracy in the preparation of cavities in a minimum amount of time, since the dentist need not change his position; and he need not hang up the contra angle on a supporting hook while picking up an air syringe to clean out the cavity, which permits the patient to change his position, and requires readjustment when the handpiece is again to be applied to the tooth with the method of the prior art.

Another object of the invention is to permit the dentist to change quickly from drilling to chip blast and back to drilling, as a single and continuous operative procedure, instead of interrupting the operation to hang the handpiece up and reach for an air syringe, as was done in the methods of the prior art; thus maximum visibility, greater accuracy in the preparation of cavities and reduction of total time are achieved, since the dentist need not change his position and the patient likewise cannot change his position, eliminating the former necessity for readiustment with respect to the changed position of the patient upon re-entering the mouth to continue the restorative procedure.

Another object is the provision of an improved foot controller for an air driven dental handpiece which is characterized by the use of a free piston and which depends upon the pressure of the air in the air manifold to bias the air controlling piston to the closed position, thereby eliminating the drag which would be caused by the use of a biasing spring.kv

3,242,572 Patented Mar. 29, 1966 A further object is to provide a system in which a single dental handpiece is used both for drilling and for blowing away cuttings, saliva, and foreign particles from a cavity, the selection of operation being made by foot manipulation of a hoor-supported foot control unit. In this connection, it is a specific object to provide a foot controller which is constructed and arranged so that either operation may be performed quickly and with little effort on the part of the dentist, but so that the dangers of performing both operations simultaneously, by inadvertent foot movement, are substantially eliminated.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there are six sheets,

FIG. 1 is a top plan view of the controller;

FIG. 2 is a side elevational View of the controller;

FIG. 3 is a vertical sectional view taken on the plane of the line 3-3 of FIG. l, looking in the direction of the arrows;

FIG. 4 is a sectional view taken on the plane of the line 4 4 of FIG. 1, looking in the direction of the arrows;

FIG. 5 is a top plan view of the controller casting showing the various conduits therein;

FIG. 6 is a horizontal sectional view taken on the plane of the line 6 6 of FIG. 2, looking in the direction of the arrows;

FIG. 7 is a fragmentary enlargement of part of FIG. 6;

FIG. 8 is a wiring diagram;

FIG. 9 is a side elevational view of an air driven dental handpiece of the type controlled Iby my foot operated controller;

FIG. 10 is an end elevational view taken from the left of FIG. 9 on an enlarged scale;

FIG. 11 is a fragmentary top plan view of the handpiece head of FIG. 9;

FIG. l2 is a fragmentary bottom plan View of the handpiece head;

FIG. 13 is an end elevational view of the turbine unit;

FIG. 14 is a vertical sectional view taken through the lhandpiece of FIG. 9 on the plane of the line 14-14 of FIG. 11, looking in the direction of the arrows;

FIG. 15 is a similar sectional view extending from the right end of FIG. 14;

FIG. 16 is a view in perspective of the air and water supply unit;

FIG. 17 is a diagrammatic view of the air and water supply unit including the conduits and locating the elements of FIG. 16.

Referring to FIGS. 1 and 2, these are top plan and side elevational views of the foot controller unit 165, which preferably comprises a metal body 2.00, which is generally rectangular in shape, having a flat top 201 and rectangular sides 202, 203, 204 with an inwardly extending rectangular slot 205 in the front side 206.

The Walls of the slot 205 are formed by a pair of forwardly projecting lugs 207, 208, which may have aligned through bores 209 for receiving a pivot pin 210, which may be secured in place by an elongated set screw 211 having a slot which is accessible from the bottom 212, the set screw being threaded into a threaded bore 213 and extending into engagement with the pivot pin 210. The set screw preferably extends into an annular groove 217 in the pin 210.

The side Wall 204 is provided with a pair of integral diagonally extending lugs 214, each of which has a 3 threaded bore 215, 216 for receiving the hose ttings 218 for attachment of the hoses 182, 183.

The pivot pin 210 serves as a pivotal mounting for a foot lever 219, which is preferably of angular shape, having an upwardly extending flange or arm 220 and a forwardly extending arm or flange 221. Both these arms are relatively wide, being as wide as the width of the slot 205 in the body 201.

The lower corner 222 of the foot lever 219 is provided with a slot extending to the dotted line 223, leaving a pair of downwardly extending lugs 224 supporting another pivot pin 225, upon which a metal roller 226 is mounted.

The body 201 supports a water ejector assembly of the type shown in FIG. 4, which is the subject of a separate application, Serial No. 857,010, tiled December 3, 1959, for Combined Filters and Water Ejectors for Air Lines; and this water ejector is mounted in a threaded bore 227, which is closed by screw plug 228.

The water ejector is for the purpose of filtering the air and separating from it the water of condensation which may have condensed in the lines leading to the foot controller, as such water tends to be mixed with the oil used, which is edible and water soluble; and such water tends also to swell the ball bearing retainers; and the water must, therefore, be eliminated.

The water ejector is mounted in the circular bore 229, which communicates with an air inlet 230 and with a smaller counter-bore 231 having a gasket 232 against which a rigid porous iilter sleeve 233 is seated and held by a metal sleeve 234 carried by screw plug 227.

The filter 233 passes water which collects in the space 235 at the end of counterbore 231 and is adapted to be discharged through the bore 236 in a threaded tting 237, which is threaded into the bore 238.

The threaded fitting 237 engages a gasket 239 by means o-f an annular flange 240, effecting a Water-tight seal at this point; and the titting 237 has a central aperture 241 against which a conical surface 242 on a piston rod 243 engages.

The piston rod has a cylindrical surface at 244 and a second cylindrical surface 245 separated by a groove 246, which has frusto-conical walls.

The fitting 237 has an internal groove 247 receiving an O ring 248 adapted to eifect a liquid-tight seal against either cylindrical surface 244 or 245, but passes water when the O ring 248V is in registry with the groove 246. Thus the aperture 241 is sealed off by the O ring 248, but is open to the discharge of water whenever the groove 246 passes the O ring by movement of the piston rod 243.

At its upper end the piston rod 243 supports a piston 249, which may have a reduced portion 250 of the rod pressed into a bore 251. The piston has a predetermined clearance at 252 in the cylindrical bore 253, passing some air at all times; and the piston has a cylindrical skirt 254 with grooves 255 and through apertures 256, passing air to the holes 257 and annular space 258 when the piston bottom surface rises above the lower edge of the internal groove in cap 228. Sleeve 234 carries an O ring 2342 in a groove to seal the lower end of the sleeve 234.

The operation of the water ejector is as follows: When the air is turned on, entering the inlet fitting 218 in the threaded bore 216, the air pressure lifts the piston 249 and momentarily the groove 246 passes through the O ring 248; and the air pressure ejects condensed water through the aperture 241. Piston 249 passes to an upper position in which the aperture 241 is closed by an O ring engaging cylindrical surfa'e 245; and further ejection of the water is prevented and passage of air is prevented at the opening 241 until the air pressure is shut 01T, when piston 249 again passes d-ownward to the position of FIG. 4, again ejecting condensed water from the aperture 241 during this motion.

The outlet from the water ejector bore 229 is by way of a bored conduit 259 to a bore or chamber 260 at the rear end of the metering valve 261, which is also in communication with a bore 262 at the bottom end of the chip air valve 263. Dry and iiltered air is controlled by either of these valves, the outlets from which are in cornmunication with each other through the cross conduit 264 and the outlet conduit 265 leading to the outlet port 215.

The metering valve 261 comprises a cylindrical member having its outer end 26.6 in position to be engaged by the roller 226 on the foot lever 219; and the metering valve 261 is slidably mounted in a cylindrical bore 267 in a screw plug 268, which has its outer threads 269 threaded into a threaded bore 270 in the body 200.

Bores 271 in the end of the plug are for receiving a spanner wrench; and the annular iiange 272 about the metering valve has a tapered groove 273 for receiving a seal ring 274, which engages the cylindrical body 275 of the metering valve, establishing a dust-tight seal at the point of engagement. An O ring 274er is carried in a groove in plunger 275, eifecting an air-tight seal with bore 322.

The screw plug 268 has a reduced cylindrical body 276 extending into counterbore 277; and a gasket 278 is clamped between the end of plug 268 and the annular surface 279 to establish an air-tight seal at this point.

The screw plug 268 has a plurality of through bores 280 extending through its reduced portion 276 to the bore 267; and the screw plug 268 carries an enlarged cylindrical end portion 281, which has a peripherally extending groove 282 supporting an O ring 283, which establishes a seal in the counterbore 277. Thus the air space 284 is sealed at both ends.

The present drive air control valve is characterized by having a free piston which is not biased by any springs, thereby avoiding the drag that is caused by spring pressure on the piston. The valve is urged to closed position by the air pressure at 289, 290 on the right end of the piston 261.

The annular edge 289 in the plug enlargement 281 at the end of bore 267 acts as a valve seat for engaging an O ring 290 contained in a groove 291, which extends about the metering valve 261 at the left side of an annular ange 292.

When the parts are in the position of FIG. 3, the valve is closed at 290, 289; but when the metering valve 261 is pushed inward toward the right, the valve is opened at 289, 290; and the metering valve 261 has a attened portion 293 which establishes a gradually increasing opening between the iiat 293 and the edge 289, gradually increasing the air flow from zero to maximum as the metering valve 261 moves inward toward the right in FIG. 3.

Thus the metering valve 261 is adapted to control the iiow of driving air from zero to maximum by means of pressure on the horizontal portion 221 of pedal 219.

The user may turn on the drive air causing the air driven handpiece to start from zero air and zero speed; and the speed may be varied gradually up to maximum or held at any desired speed by holding the foot pedal 219 at any desired position.

The foot pedal 219 is preferably actuated by pivoting the foot on the heel or the ball of the foot; and the flow of air is automatically stopped by lifting or removing the toe from the lever 219.

The chip air valve 263 comprises a cylindrical metal member having its outer cylindrical surface 294 slidably engaged in a bore 295 in a second screw plug 296. The screw plug 296 has an enlarged threaded portion 297 threaded into a threaded bore 298 in the body 200; and the enlarged threaded portion 297 engages a gasket 299 seated at 300 in the threaded bore 298, effecting an air seal at this point.

The screw plug 296 has a reduced cylindrical body 301 which slides into a smaller counterbore 302 and is provided with a groove 303 carrying a rubber O ring 304, effecting a seal at this end of the body 301. Between the O ring 304, and gasket 300 the reduced body 301 has an annular groove 305, which is in communication with the cross port 264 and with the outlet 215.

There is another annular groove 306 on the inside of the bore 295 and a plurality of through apertures 307 joining the groove 305 and 306.

The edge of the reduced plug 301 at the end of bore 295 Vis indicated at 308 and serves as a valve seat to be engaged by an O ring 305 which is seated in a groove 310 above an annular tiange 311 on the end of the chip air valve 263.

The chip air valve 263 also has a flattened portion 312, establishing a conduit from a point inside the O ring 308 to the groove 306, so that when the chip air valve is opened at 310 and 308, air may flow from the bore 262 backward along the chip air valve 263 at the {lattened portion 312 to the groove 306, apertures 307, groove 305, and cross port 264, which is in communication with the outlet 215.

The chip air valve 263 also has an annular groove 313 containing a rubber O ring 314, eifecting a seal between the valve member 263 and the upper end of the bore 295. At its upper end the valve member 263 may have a tapered portion 315 receivable in a tapered bore 316 in a foot actuated disc 317, which is secured on the plunger 263 by a flush head screw bolt 31S threaded into a threaded bore 319 in the valve plunger 263.

The present chip air valve is characterized by the absence of any biasing spring, thereby eliminating the drag which is caused by having a spring urging the disc 317 upward. As the chip air valve has a free piston, it is urged to closed position only by the air pressure in the bore 262.

The volume and presence of the chip air is controlled at the control unit for the air driven handpiece; and the chip air valve 263 is used for turning on the chip air with the foot on the disc 317 whenever the user wishes to clean out a. cavity; and for this purpose he must remove his foot from the air control pedal 219, so that the handpiece is always stopped when cleaning chip air is used.

Referring to FG. 6, this is a sectional view taken through the body 200 on a horizontal plane, showing the location of the air valve plunger 261 inside the slot 205 adjacent the electrical plunger 321 for controlling the electrical circuits by means of which the solenoid valves are actuated for controlling the flow of drive air, chip air and water.

The body 200 has a cylindrical bore 322 for slidably receiving the electrical plunger, the end 323 of which projects farther than the air plunger 261 so that the electrical plunger is adapted to be actuated rst, prior to the initial opening of the metering valve. This action sequence provides for the unloading of the control cabinet manifold pressure and prevents an initial surge of air at starting, which would cause the handpiece burr tube to rotate unexpectedly.

The electrical plunger 321 has a reduced portion 324 between two cylindrical portions 325 and 326; and there are truste-conical portions 327 and 328 at each end of the reduced portion for camming a roller 329 outward. At its inner end 330 the electrical plunger 321 has a cylindrical bore 331 receiving a coil spring 332, which has its other end seated on a central pin 333.

Spring 332 urges the electrical plunger outward to the position of FIGS. 6 and 7.

The cylindrical bore 322 communicates with a cavity 334 by means of a window opening 335 extending to the bore; and the cavity 334 houses a mieroswitch unit 336, which is secured by a pair of screw bolts 337, and which has three electrical terminals 338, 339 and 340.

A leaf spring 341 is secured by screw bolts 337 to one end of the switch unit 336 in position to engage a switch button 343, but is biased away from the switch button. The leaf spring 341 carries at its end a U- shaped stirrup 344 having a pivot pin 345 rotatably mounting the roller 329.

The corresponding terminals 338, 339 and 340 are shown at the switch unit 336 in the wiring diagram of FIG. 8.

The microswitch 336 is of the type having the snap button 343 normally on open circuit at 340 and on closed circuit at 338. When the button 343 is pressed inward by leaf spring 337, the switch unit 336 opens at the contact 338 and closes at the contact 340; but when the plunger 321 is released by lifting the foot on the air control pedal 219, the button 343 moves to the position of FIG. 8 and FIG. 6 with the circuit closed at 338 and open at 340.

The operation of the electrical plunger 321 is as follows: When the foot pedal 219 is pressed, and before the `air metering valve 261 is opened, the camming surface 327 engages roller 329 and moves leaf spring 341 into engagement with button 343, which is pressed inward to close the circuit at 340 and open the circuit at 338.

The roller 329 is then riding on the cylindrical surface 325 as long as the foot pedal is pressed inward. When the foot pedal is released, the parts again move to the position of FIG. 6, opening the circuit at 340 (FIG. 8).

Referring to FIGS. 9-15, these are views illustrating the air driven dental handpiece, which is driven and controlled by the foot controller. The handpiece 30 (FIG. 9) has a tubular handle 31 with an obtuse angle 32 and a neck 33 supporting the contra angle head 34.

This head comprises a substantially cylindrical housing 3S tapered at its lower end at 36 and having one end 37 open to expose the shaft and the other end closed by a threaded cap 48. Cap 48 has a central aperture 50 for passing air carrying lubricant mist, which lubricates the ball bearings at this end of the housing; and the apertures 51 are for a Spanner wrench.

The cap 48 is rounded at 52 to join with the head housing.

Referring to FIG. l2, this is a fragmentary bottom plan view of the head 34, which is tapered down to the annular end surface 37, having a circular aperture 33 for exposing the end of the shaft 39, which has a tubular bore 42 frictionally securing a plastic chuck sleeve 43 having a cylindrical bore 44 for gripping the shank of a burr 112.

There is a clearance 40 between the annular end 41 of the shaft 39 and the bore 38 which acts as an air nozzle directing air in a conical direction toward the end 111 of the burr 112. this also being part of the drive air which lubricates the lower bearings with air mist.

The neck 33 has brazed to it the nozzle conduits 144 for water and 145 for chip air, each of which has its end directed to discharge water or air toward `the burr 111; and the controls are so arranged that the drive air and cooling water from the nozzle 144 are turned on at the same time or olf at the same time.

When they are olf, the chip cleaning air from nozzle 145 may be turned on by means of the foot to clean out the cavity without removing the handpiece from the mouth.

Referring to FIG. 13, this is an elevational view of the air turbine unit 58, which is preferably removable from the head housing 35, as it has a cylindrical shell 67, which tits in the head housing bore. Shell 67 has a laterally extending lug 72 (FIG. 14) which slides in an axial groove inside the head housing 35 and locates the inlet aperture 138 for drive air and the outlet aperture for exhaust air in proper position to register with the conduits 139 and 140 located in the neck 33.

The shell 67 extends inward at the bottom to engage the top of the lower outer race 106 of the lower ball bearing assembly 61. The top of the shell 67 engages the upper ange of a stator 77, which has an annular groove S1 registering with the air inlet conduit 139.

The upper ball bearing assembly 57 has its outer race seated in a bore in the stator 77; and the top of the outer race is engaged by the cap 48.

The shaft 39 carries a cylindrical rotor 105 which has a tubular extension 93 engaging the upper inner race and another tubular extension 92 engaging the lower inner race, which race is seated against an annular shoulder on the frusto-conical head 65, which defines the annular conical nozzle 40.

The conical nozzle 40 is slightly enlarged at 66 at its end to increase the amount of air discharged; and the water from the water nozzle 144 is caused to rotate and is atomized by being sprayed into the conical air spray from the annular nozzle 40.

The upper inner race is secured to the shaft by the screw cap 102; and the balls in the races hold the ball bearings in assembled condition and make the turbine assembly 58 a removable unit.

The water and air conduits 144, 145 pass into the handle at the neck 33 (FIG. 14) and are connected to electrical conductors so that these conduits, which are of electrical resistance metal, may serve as heaters, if desired.

In other embodiments heaters for heating the water and the air may be located in the control unit, which is shown in FIG. 16.

Referring to FIG. 16, this is a view in perspective of a control cabinet 350, which is provided with a forked arm 351 for supporting the handpiece 30.

FIG. 17 is a diagram showing the most important parts of the control cabinet, which includes a water inlet 352 leading to a water filter 353. A conduit 354 extends -to a water pressure regulator 355 from which a conduit 356 extends to a water solenoid valve 357, which controls a Water outlet to the handpiece, also including a metering needle Valve 358. Thus the volume and pressure of the Water may be regulated, and the water may be turned on or olf electrically.

The air supply inlet is indicated at 359, extending to an air lilter 360, which has a conduit extending to an air pressure regulating valve 361, the outlet of which is connected by conduit 362 to an air solenoid valve 363, which controls the flow of air to a lubricator. A further conduit 364 extends to a third solenoid valve 365 having a needle valve 366 for controlling chip air.

The outlet from the drive air solenoid 363 is indicated at 367; and it is connected to the lubricator (not shown), which provides the drive air with lubricant in the form of a mist that lubricates the ball bearings by passing through the ball bearings about the balls.

The present foot controller has its inlet 183 conneted to the air compressor, and its outlet 182 connected to the air inlet 359 (FIGURE 17) of the control cabinet.

The further details of the control unit are shown in my prior application Serial No. 798,866, tiled March l2, 1959, on Control Unit for Air Driven Dental Handpieces, of which this is a continuation-in-part, the specification and drawings of which are hereby incorporated herein by reference thereto.

Referring to the wiring diagram of FIG. 8, 368 indicates the back plate of insulation and 369 the front plate of insulation of a rotary switch indicated `at 370 in FIG. 16. This rotary switch has two rotating annular contacts 371 and 372 which are in the open position at the line contact 373 and the other contact 374.

The 110 volt 60 cycle line -is indicated at 375 and 376; and the latter conductor 376 extends to the common terminal 339 of the microswitch, which is adapted to control the handpiece by control of this line conductor.

The rotary switch 370 has a left hand position, indicated by the word Spray in FIG. 8, in which fixed contact 377 is closed.

When the rotary switch is rotated to the left to the Spray position, the circuit is conditioned to close the water solenoid 357 and the drive air solenoid 363.

When the switch is turned to the right hand position, as indicated by the word Ain the circuits are conditioned for the closing of the chip air solenoid 365; but this solenoid is also controlled by the microswitch 336 so that the user may turn on the chip air after turning off the drive air and water to blow air into the cavity to clean it out and to dry the cavity without removing the handpiece, and then grinding may be resumed.

It will thus be observed that I have invented an improved control system by means of which the user may control the `speed of operation of the handpiece from zero to maximum; and by removing his foot from the speed control pedal the user may open the chip air valve, all of which is accomplished by the foot, leaving the hands of the user free for other operations.

While I have illustrated a preferred embodiment of my invention, many modifications may be made Without departing from the spirit of the invention; and I do not wish to .be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A foot-operated control system for air-driven dental handpieces, comprising a foot controller including a low, Hat-topped metal body adapted to rest upon a oor surface and having a chamber adapted to communicate with a source of air under pressure, a drive air control valve assembly mounted within said body and including a foot pedal having a generally horizontal portion projecting outwardly from one side of the body at a point spaced substantially below the flat top of said body, said pedal being depressible by foot pressure to open the valve of said assembly and to permit air under pressure to ow from said chamber through said assembly, an air-driven dental handpiece having a chip air nozzle, passage means communicating with said valve assembly and with said handpiece for conducting air under pressure to the driving mechanism of the air driven dental handpiece when said pedal is depressed, and a chip air valve assembly mounted in a vertical threaded bore extending downwardly into said body and including a control button positioned above and in close proximity to the top surface of said body substantially above the level lof the horizontal portion of said foot pedal and at a spaced horizontal distance from said horizontal portion, said chip air valve assembly including a valve plug threadedly mounted in said bore and having a vertical and generally cylindrical passage extending therethrough and also having at least one side aperture communicating with said passage, said passage of said plug communicating at its lower end with said chamber of said body, internal passage means provided by said body and communicating through said bore with the side aperture of said plug, conduit means externally of said body communicating at one end thereof with said internal passage means and at the other end thereof with said chip air nozzle of said dental handpiece for conducting chip-clearing air from said foot controller to said chip air nozzle, and a plunger vertically slidable between lowered and raised positions within the passage of said valve plug and having its upper end secured to said control button, said plunger having a vertical length greater than the passage of said plug and being provided with an enlargement disposed beneath the lower end of said plug for limiting the extent of upward movement of said plunger, said plunger also being provided with a recess for placing the chamber of said body in communication with the side aperture of said plug only when said plunger is in lits lowered position, said plunger being normally maintained in its raised position by the pressure of air in said chamber, whereby, the relative positions of said pedal and said control button permit selective operation ofthe driving mechanism of said handpiece and the discharge of chip-clearing air from the handpiece nozzle without danger of performing both operations simultaneously,

2. The structure of claim 1 in which said enlargement of said plunger is at the lower extreme end thereof and is in the form of an annular disk portion having a diameter larger than the passage of said plug, said plunger being urged upwardly solely by the pressure of air within said chamber.

3. The structure of claim 2 in which said annular disk portion of said plunger has an upper frusto-conical surface engageable with the lower end of said plug.

References Cited bythe Examiner UNITED STATES PATENTS Little 13T-234.5 Diener 251-295 X Muend 251--295 X Fraser 251--295 X Killner 137-2345 Lynch 137-599 X Anderson 251-295 X Hammon IS7-454.2

ISADOR WEIL, Primary Examiner.

15 ALAN COHAN, Examiner. 

1. A FOOT-OPERATED CONTROL SYSTEM FOR AIR-DRIVEN DENTAL HANDPIECES, COMPRISING A FOOT CONTROLLER INCLUDING A LOW, FLAT-TOPPED METAL BODY ADAPTED TO REST UPON A FLOOR SURFACE AND HAVING A CHAMBER ADAPTED TO COMMUNICATE WITH A SOURCE OF AIR UNDER PRESSURE, A DRIVE AIR CONTROL VALVE ASSEMBLY MOUNTED WITHIN SAID BODY AND INCLUDING A FOOT PEDAL HAVING A GENERALLY HORIZONTAL PORTION PROJECTING OUTWARDLY FROM ONE SIDE OF THE BODY AT A POINT SPACED SUBSTANTIALLY BELOW THE FLAT TOP OF SAID BODY, SAID PEDAL BEING DEPRESSIBLE BY FOOT PRESSURE TO OPEN THE VALVE OF SAID ASSEMBLY AND TO PERMIT AIR UNDER PRESSURE TO FLOW FROM SAID CHAMBER THROUGH SAID ASSEMBLY, AN AIR-DRIVEN DENTAL HANDPIECE HAVING A CHIP AIR NOZZLE, PASSAGE MEANS COMMUNICATING WITH SAID VALVE ASSEMBLY AND WITH SAID HANDPIECE FOR CONDUCTING AIR UNDER PRESSURE TO THE DRIVING MECHANISM OF THE AIR DRIVEN DENTAL HANDPIECE WHEN SAID PEDAL IS DEPRESSED, AND A CHIP AIR VALVE ASSEMBLY MOUNTED IN A VERTICAL THREADED BORE EXTENDING DOWNWARDLY INTO SAID BODY AND INCLUDING A CONTROL BUTTON POSITIONED ABOVE AND IN CLOSE PROXIMITY TO THE TOP SURFACE OF SAID BODY SUBSTANTIALLY ABOVE THE LEVEL OF THE HORIZONTAL PORTION OF SAID FOOT PEDAL AND AT A SPACED HORIZONTAL DISTANCE FROM SAID HORIZONTAL PORTION, SAID CHIP AIR VALVE ASSEMBLY INCLUDING A VALVE PLUG THREADEDLY MOUNTED IN SAID BORE AND HAVING A VERTICAL AND GENERALLY CYLINDRICAL PASSAGE EXTENDING THERETHROUGH AND ALSO HAVING AT LEAST ONE SIDE APERTURE COMMUNICATING WITH SAID PASSAGE, SAID PASSAGE OF SAID PLUG COMMUNICATING AT ITS LOWER END WITH SAID CHAMBER OF SAID BODY, INTERNAL PASSAGE MEANS PROVIDED BY SAID BODY AND COMMUNICATING THROUGH SAID BORE WITH THE SIDE APERTURE OF SAID PLUG, CONDUIT MEANS EXTERNALLY OF SAID BODY COMMUNICATING AT ONE END THEREOF WITH SAID INTERNAL PASSAGE MEANS AND AT THE OTHER END THEREOF WITH SAID CHIP AIR NOZZLE OF SAID DENTAL HANDPIECE FOR CONDUCTING CHIP-CLEARING AIR FROM SAID FOOT CONTROLLER TO SAID CHIP AIR NOZZLE, AND A PLUNGER VERTICALLY SLIDABLE BETWEEN LOWERED AND RAISED POSITIONS WITHIN THE PASSAGE OF SAID VALVE PLUG AND HAVING ITS UPPER END SECURED TO SAID CONTROL BUTTON, SAID PLUNGER HAVING A VERTICAL LENGTH GREATER THAN THE PASSAGE OF SAID PLUG AND BEING PROVIDED WITH AN ENLARGEMENT DISPOSED BENEATH THE LOWER END OF SAID PLUG FOR LIMITING THE EXTENT OF UPWARD MOVEMENT OF SAID PLUNGER, SAID PLUGER ALSO BEING PROVIDED WITH A RECESS FOR PLACING THE CHAMBER OF SAID BODY IN COMMUNICATION WITH THE SAID APERTURE OF SAID PLUG ONLY WHEN SAID PLUNGER IS IN ITS LOWERED POSITION, SAID PLUNGER BEING NORMALLY MAINTAINED IN ITS RAISED POSITION BY THE PRESSURE OF AIR IN SAID CHAMBER, WHEREBY, THE RELATIVE POSITIONS OF SAID PEDAL AND SAID CONTROL BUTTON PERMIT SELECTIVE OPERATION OF THE DRIVING MECHANISM OF SAID HANDPIECE AND THE DISCHARGE OF CHIP-CLEARING AIR FROM THE HAND PIECE NOZZLE WITHOUT DANGER OF PERFORMING BOTH OPERATIONS SIMULTANEOUSLY. 